Fiber-optic communications allow for optical transmission of information with various advantages over electrical transmission via copper wires. For example, fiber optic cables may allow very high bandwidth transmissions with very low loss compared to copper wire. In various applications, optical fibers may be bundled together into transmit-receive pairs, and multiple transmit-receive pairs may be bundled together to create a multi-channel cable. It may be desirable, therefore, to confirm that each output of a multi-channel cable corresponds to the correct input of the multi-channel cable.